专用核糖体如何翻译一个无领导的mRNA
Francisco J Acosta-Reyes1, Sayan Bhattacharjee1, Max Gottesman2
1Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
Journal of molecular biology
|January 7, 2024
概括
菌体 λ无领导的mRNA (lmRNA) 翻译在核糖体蛋白 uS2-缺乏突变体中得到增强. 化EM揭示了核糖体结构的变化如何促进lmRNA的输入和翻译,为这个保存过程提供了洞察力.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 微生物学 微生物学
背景情况:
- 细菌的lambda (λ) lysogens利用无领导的mRNA (lmRNA) 来产生 λcI抑制剂,该抑制剂由 λpRM 促进物启动.
- 在缺乏核糖体蛋白 uS2.2 的大肠杆菌突变体中,lmRNA的翻译显著增强.
- 了解lmRNA翻译启动的结构基础至关重要,因为它在细菌,古生物和真核生物中保存.
研究的目的:
- 阐明在US2缺陷核糖体中增强的λcI lmRNA转化背后的结构机制.
- 为了提供高分辨率的结构洞察力,对lmRNA翻译启动复杂.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 来确定野生类型和US2-缺陷 (rpsB11突变) 70S核糖体的结构.
- 综合体包括lcI lmRNA和启动器tRNA (fMet-tRNA).
主要成果:
- 缺乏US2的核糖体,也缺乏bS21,表现出改变的抗Shine-Dalgarno (aSD) 区域定位,从而促进lmRNA的退出.
- 核糖体基A1493和lmRNA A(+4) 之间的π堆叠相互作用可以作为识别信号.
- 核糖体动态,包括增加30S头旋转和潜在电荷流,可能有助于lmRNA的传播.
结论:
- uS2和bS21的缺失从结构上重新配置了核糖体,促进了无领导的mRNA翻译.
- 特定的相互作用和动态机制促进lmRNA结合和通过核糖体.
- 这些发现为研究翻译机制和lmRNA和核糖体的共同进化提供了结构基础.
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